Re: evum constructor gotcha

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 02 Aug 2009 20:02:05 -0400

Message-ID:

<h559e0$uth$1@news.albasani.net>

Lew wrote:

markspace wrote:

Lew wrote:

Actually, you picked a bad example. THE_ANSWER is a compile-time
constant and will not be initialized at all, rather, it will be used
as the compiled-in value 42.

On my system, that construct gives "Illegal forward reference," unless
I messed something else up.

You are absolutely correct. I should have tried it first.

Here's a way around it:

<code>
package testit;
public enum ForwardRef
{
     FIRST( Holder.THE_ANSWER ),
     SECOND( Holder.THE_ANSWER );

     static class Holder
     {
         static final int THE_ANSWER = 42;
     }
     private final int value;

     private ForwardRef( int value )
     {
         this.value = value;
     }
     public int getAnswer()
     {
         return this.value;
     }
}

//===

package testit;

/** ForwardReferee.
  */
public class ForwardReferee
{
     public static void main( String [] args )
     {
         for ( ForwardRef fr : ForwardRef.values() )
         {
             System.out.print( "ForwardRef."+ fr );
             System.out.println( ".answer = "+ fr.getAnswer() );
         }
     }

}
</code>
<output>
$ javac -d ~/projects/testit/build/classes \
   testit/ForwardRef.java testit/ForwardReferee.java

$ java -cp ~/projects/testit/build/classes \
   testit.ForwardReferee
ForwardRef.FIRST.answer = 42
ForwardRef.SECOND.answer = 42
$
</output>

--
Lew